Grantlee::variantIsTrue() was not properly checking whether a QVariant
containing a float (for example a qreal on arm and sh platforms)
is a true value, simply because its type was not be handled in the type
switch, and thus it was handled as string.
Adding the QMetaType::Float case and extracting the float as such from
the variant fixes the issue.

The test data for TestDefaultTags::testIfTag() has been expaded to
include if-truthiness data explicitly for double and float values,
so the they can be both tested no matter what qreal is.